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Multisystem 1st Half > antiviral agents > Flashcards

antiviral agents Flashcards

1
Q

acyclovir and derivatives are used to treat…

A

herpes virus

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2
Q

hsv1
hsv2
vzv

A

1 - oral herpes and herpes keratitis
2 - genital herpes
vzv - chicken pox and shingles

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3
Q

acyclovir

structure and mechanism of action

A

guanosine analog with an acyclical sugar

used to treat herpes viruses

• Acyclovir does NOT cure herpes infection; it suppresses and shortens outbreaks

  • Mechanism of action = chain termination
  • REQUIRES viral thymidine kinase enzyme for activation from pro-drug to active form (host enzymes will not do this primary phosphorylation)

gmp –> gtp

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4
Q

NRTIs used to treat HIV vs acyclovir for HSV

A

• REQUIRES viral thymidine kinase enzyme for activation from pro-drug to active form (host enzymes will not do this primary phosphorylation)
o In contrast, NRTIs used to treat HIV use host-encoded nucleoside kinases for activation

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5
Q

valaciclovir

A
  • A valine ester of acyclovir

* Activated in liver  achieves higher serum levels due to greater bioavailability

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6
Q

NRTIs

A

NRTIs (nucleoside reverse transcriptase inhibitors) = ZEAL (zidovudine, emtricitabine, abacavir, lamivudine) + DT (didanosine, tenofovir)

all are prodrugs that require cellular kinases (phosphorylation) for activation (thymidine kinase)

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7
Q

zidovudine (AZT)

A

NRTI
mechanism: 1) competitive inhibition of HIV reverse transcriptase(RT) and 2)premature chain termination

Decreases HIV progression

o Side effects: macrocytic anemia and neutropenia; potential to induce lactic acidosis (DNA pol gamma)

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8
Q

is zidovudine safe for pregnanct?

A

yes

reduces transmission of HIV to offspring

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9
Q

emtricitabine

A

NRTI, used to treat HIV and HBV

fluorinated analog of lamivudine with longer half life

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10
Q

abacavir

A

NRTI with hypersensitivity reactions

hepatomegaly (especially in HLA-B5701 patients; only give after you genotype the patient

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11
Q

what are the 6 NRTIs?

what do they require to work?

what are they used to treat?

A 
zidovudine
emtricitabine
abacavir
lamivudine
didanosine
tenofovir
ZEALDT

require thymidine kinase for activation

treat HIV and hepB

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12
Q

what does thymidine kinase do for NRTIs

A

phosphorylates them to turn them from prodrugs to activated drugs

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13
Q

lamivudine (3TC)

A

NRTI; used for HIV and hepB

LOW side effects:) great for pregnancy use

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14
Q

didanosine

A

NRTI, with risk of pancreatitis, peripheral neuropathy, and severe liver problems

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15
Q

tenofovir

A

NRTI that is a nucleotide analog that competitively inhibits HIV RT and causes chain termination; used for HBV and HIV

a nucleoside phosphonate that is converted to di and triphosphate in resting cells –> doesnt require initial phosphorylation for activation);

watch for renal toxicity

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16
Q

NNRTIs

A

non-nucleoside RT inhibitors

(names contain -vir-) nevirapine, rilpivirine, etravirine, efavirenz, delaviridine =RNEED

do not require phosphorylation to be active
do not compete with NRTIs or nucleotides for RT binding –> no cross resistance since they work at different sites!

but high potential for drug interactions –> they inhibit and induce cyp3a4

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17
Q

unlike NRTIs, NNRTIs….

A

do not require phosphorylation for activation

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18
Q

can NRTIs be used with NNRTIs?

A

yes
they do not compete with NRTIs or nucelotides for RT binding –> no cross-resistance since they are working at different sites

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19
Q

why is there high potential for drug interactions with NNRTIs?

A

they all inhibit or induce cyp3a4

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20
Q

nevirapine

A

NNRTI, for HIV
prophylaxis for pregnant women

can cause stevens johnson syndrome

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21
Q

rilpivirine

A

very high cross resistance, cannot use with other NNRTIs

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22
Q

etravirine

A

good for patients who are resistant to other NNRTIs

23
Q

efavirenz

A

NNRTI; NOT TO BE USED with pregnancy –> fetal defects

24
Q

delaviridine

A

NNRTI

inhibits cyp3a4 and causes skin rashes

25
Q

which nnrti should be used with pregnancy? not be used with pregnancy?

A

P- nevirapine

not with P - efavirenz

26
Q

if an HIV patient is resistant to most NNRTIs, which should be used?

A

etravirine

27
Q

many HIV patients are also co-infected with what?

A

hep B (HBV)

28
Q

HIV vs HBV

A

HIV is a retro virus and HBV is a DNA virus

both use reverse transcriptase

29
Q

what is HBV?

A

a DNA virus that can be transmitted sexually or through infected blood

causes chronic liver disease (hepatitis and cirrhosis)

there is a vaccine

30
Q

best two NRTIs that treat both HIV and HBV

A

lamivudine

tenofovir

31
Q

1st line drugs for HBV

A

all DNA polymerase/reverse transcriptase inhibitors
=HBV LATTE

lamivudine
adefovir (nucleotide RTI)
tenofovir (nucleotide RTI)
telbivudine (thymidine analog)
entecavir (guanosine analog)
32
Q

mechanism for HIV cell attachment

A

HIV infects CD4+ helper T cells, macrophages, and dendritic cells.

GP120 binds CD4 receptor and CCR5 receptor (chemokine co-receptor)

binding of gp120 causes conformational changes that enables gp41 to fuse virus and host cell membrane –> 2 gp41 molecules pull the virion into the cell!

33
Q

2 drugs that are HIV virus binding inhibitors

A

maraviroc

enfuvirtide

34
Q

maraviroc

A

HIV drug that inhibits binding of gp120 to CCR5 (chemokine receptor 5)

will NOT work if the viral strain uses the CXCR4 receptor instead of CCR5 (so genotype the virus first!)

35
Q

enfuvirtide

A

HIV drug that locks gp41 in the extended conformation –> inhibits fusion of virus and host cell

36
Q

provirus and integrase

A

a provirus is viral DNA that is integrated into the host chromosomal DNA by the enzyme integrase

37
Q

INSTIs

A

integrase strand transfer inhibitors

oral HIV drugs that inhibit integrase from integrating viral DNA into chromosomal host DNA

raltegravir
elvitegravir
dolutegravir

38
Q

any drug that ends with -gravir does what?

A

inhibits integrase; treats HIV

raltegravir
elvitegravir
dolutegravir

39
Q

protease involvement in HIV virus?

A

during maturation, the protease enzyme cleaves polyprotein to Gag proteins, resulting in new infectious virions.
• Without Protease, viral particles would be non-infectious; it is important for processing them into functional virions
• HIV protease (PR), integrase, RNase H, and reverse transcriptase (RT) are initially expressed as a Gag-Pol fusion protein
o In maturation, HIV protease cleaves the gag-pol polypeptide to separate the protease, RT, RNase, and integrase

40
Q

HIV protease inhibitors

A

all end in -avir

do not require any modification for activation

use in combination (ritonavir + darunavir, lopinavir, saquinavir, or tipranavir)

always w ritonavir since ritonavir increases the concentration of other protease inhbitors (synergistic)

41
Q

HIV protease inhibitor with lower incidence of lipodystrophies?

A

atazanavir

42
Q

HIV protease inhibitor combo recommended with pregnancy

A

lopinavir

ritonavir

43
Q

side effects of using HIV protease inhibitors

A

redistributed body fat (central obesity, dorsocervical fat (buffalo hump), facial wasting) (LIPODYSTROPHIES)

–increased LDL, decreased HDL, increased triglycerides hyperglycemia, insulin resistance

44
Q

PrEP

A

preexposure prophylaxis for HIV in high risk groups

truvada = emtricitabine + tenofovir

45
Q

what is hepatitis C?

A

parenteral transmission; risk factors = exposure to mucosal surfaces, sharing contaminated needles and unprotected sex with infected partner, transfusion

many infected people develop viral persistence

causes liver transplantation and Hepatocellular carcinoma.

46
Q

treatment for hepC

A

triple therapy

boceprevir or telapravir +
Peg-IFN +
ribavirin

47
Q

4 drugs for hepC

A

interferons
ribavirin
sofosbuvir
Hcv protease inhibitors (-previr)

48
Q

interferons as hcv drug

A

Interferon alphas have general antiviral activity (hepatitis B and C)

Most effective against C when used in combination with ribavirin

reduce development of chronic infections if taken during acute phase

Pegylated forms (Peg-IFN) have improved pharmacokinetic properties

49
Q

side effects of interferons in HCV treatments

A

SIDE EFFECTS: flulike - fever, headache, muscle ache, chills Can affect compliance.

50
Q

ribavirin

A

Broad-spectrum antiviral drug; used in combination with IFN alpha for HCV.

Inhibits purine biosynthesis, interferes with RNA metabolism needed for viral replication. Requires kinase activation.

51
Q

treatment for RSV (respriatory syncytial virus?

A

aerosolized ribavirin

52
Q

HCV protease inhibitors

A

boceprevir, telaprevir, simeprevir

used in combination therapy with other HCV

Used with ribavirin and INFα

53
Q

sofosbuvir

A

HCV treatment drug
—-Inhibits HCV RNA synthesis; Substrate of NS5B polymerase

Pro drug (requires kinases for activation via phosphorylation)

pan-genotypic antiviral–>approved for gentotypes 1-4

Multisystem 1st Half (23 decks)

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